V-  A.  (r<xn^-. 


Si~udte$  0-f-  The,  LrocsoB / ne,  Jzx~t~r'oic,-f~'  Of- 

pi^iTczl r&  Leave#  . 


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Iii 


■ M. 


STUDIES  OF  THE  GASOLINE  EXTRACT 


OF 


DIGITALIS  LEAVES 


BY 


VIRGIL  A.  GANT 


THESIS 


FOR  THE 


DEGREE  OF  BACHELOR  OF  SCIENCE 


IN 


COLLEGE  OF  LIBERAL  ARTS  AND  SCIENCEwS 


UNIVERSITY  OF  ILLINOIS 


1921 


Digitized  by  the  Internet  Archive 
in  2015 


https://archive.org/details/studiesofgasolinOOgant 


UNIVERSITY  OF  ILLINOIS 


\$%\ 


1 


Hjl I92_A_ 


THIS  IS  TO  CERTIFY  THAT  THE  THESIS  PREPARED  UNDER  MY  SUPERVISION  BY 

-YJDiGLIL-JL* GAHT. 

ENTITLED..SXIIDI]i:a-QZ-l^-[>ASiILnrK^TRACX-iIg-JDiaiXAUIS--LEAV£a 


IS  APPROVED  BY  ME  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR  THE 
degree  of  __  Baj3he_lP_r__of  


Instructor  in  Charge 


Approved 


HEAD  OF  DEPARTMENT  OF 


/OO 


*3u : t ci  C C>0 


I 


TABLE  OP  CONTENTS 


introduction 


Page 


Discussion  of  the  Problem  1 

Historical  2 

Properties  and  Nature  of  Pats  and  Waxes  3 

Part  X.  Analysis  of  the  Gasoline  Extract  of 

Digitalis  Leaves  5 

Part  II.  Analysis  of  gasoline-free  and  chlorophyl- 

free  fatty  acids  9 

Conclusions  12 

Bibliography  17 


Acknowledgment 


To  Dr.  George  D.  Beal,  who,  by  his  kind,  careful,  and 
willing  supervision,  has  caused  me  to  go  into  this  work 
with  a heart-felt  and  whole-hearted  purpose,  I wish  to 
extend  my  most  sincere  feeling  of  gratitude. 


' 

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♦ 

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♦ 


INTRODUCTION 


Discussion 

One  of  the  greatest  problems  in  the  manufacture  of  chemical 
and  phama  cent  i cal  products  to-day  is  the  utilization  or  disposal 
of  by-products*  Sometimes  the  by-products  are  such  that  they  are 
harmful  to  life  in  the  region  around  the  plants,  and  must  be  dis- 
posed of  as  quickly  as  possible*  More  often,  however,  the  by- 
products give  promise  of  being  of  some  use  to  man,  and  it  then  be- 
comes the  duty  of  the  chemist  to  find  a use  for  this  product  which 
might  otherwise  be  thrown  away  and  lost* 

In  the  manufacture  of  the  heart-tonic,  Digitol,  there  is  a 
certain  amount  of  vegetable  fat  in  the  compound,  which,  if  not  re- 
moved will  become  rancid  ornstrong"  and  thus  lessen  the  pharmaceu- 
tical value  and  keeping  qualities  of  the  tonic*  This  rancidity  is 
thought  to  be  due  to  certain  unsaturated  fatty  acids  which  have 
foul  odor  when  oxidized*  Hence,  in  order  to  avoid  this  undesirable 
quality  the  leaves  of  the  digitalis  plant  are  first  extracted  with 
gasoline  in  order  to  completely  dissolve  the  vegetable  fats*  Gaso- 
line is  used  because  it  dissolves  the  fats  and  leaves  behind  the 
valuable  proximate  principles*  This  gasoline  extract,  also,  con- 
tains much  chlerophyl  from  the  leaves.  It  is  important  that  the 
chlorophyl  be  removed  from  the  tonic  because  it  must  be  clarified 
in  order  to  be  attractive* 

The  problem  has  been  to  determine  the  nature  of  the  gasoline 
extract  and,  if  possible,  the  character  of  the  various  extractive^ 
It  has  included  the  study  of  the  extract  perse,  with  the  determina- 
tion of  the  unsoponifiable  matter,  largely  gasoline  residues;  the 


- 

. 


r 


-2- 

character  of  the  gasoline  free  extract,  and  a study  of  the  chlere- 
phyl-free  fatty  matter.  The  methods  of  analysis  followed  have  been 
largely  those  of  the  Association  of  Official  Agricultural  Chemists, 
with  frequent  reference  to  Lewkowttsch,  Technology  of  Oils,  Fats 
and  Waxes  on  questions  dealing  with  the  interpretation  of  results 
and  special  separations. 

Historical 

Digitalis  Foluim  of  the  gardens,  grown  as  an  ornamental  flow- 
ering plant  is  the  common  Foxglove.  The  variety  most  commonly  used 
medicinally  is  Digitalis  purpurea  Linne  ( Fam. Scrophulariaceae ) • 

The  dried  leaves  of  the  plant  constitute  the  official  part  and  are 
used  without  the  presence  or  admixture  of  more  than  2 percent,  of 
stems,  flowers  or  other  foreign  matter.  The  leaves  when  entire  at- 
tain a length  of  30  cm.  and  a breadth  of  15  cm. , ovate  to  oval  a- 
bruptly  contracted  into  winged  petioles,  the  latter  from  5 to  10cm. 
in  length,  or  in  the  smaller  leaves,  nearly  absent;  margin  crenate, 
irregular  (the  commercial  article  usually  more  or  less  crumpled  and 
broken),  thin,  dull,  pale  green  or  gray  and  densely  pubescent  on  the 
lower  surfaces;  upper  surfaces  wrinkled  and  sparsely  hairy;  the 
midribs  flat  and  the  principal  veins  broad  and  purple;  odor  slight; 
taste  strongly  bitter.1  The  leaves  are  carefully  plucked  and  clean- 
ed so  as  not  to  have  dirt  clinging  to  them.  The  lower  leaves  of  the 
plant,  especially  when  grown  on  a loose  loamy  soil,  will  have  the 
highest  ash  content,  due  to  earthy  material,  and  even  the  upper 
leaves  will  have  a higher  ash  content  if  gathered  soon  after  a 
splashing  rain.  After  drying, they  are  pulverized,  giving  a dark 
green  powder.  From  this  powder,  the  various  preparations  such  as 


r 


-3- 


Fluidextractum  Digitalis,  Infusum  Digitalis,  and  Tincture  Digitalis 
are  made*1' 

Properties  and  nature  of  Fats  and  Waxes, 

Fats  and  waxes  are  both  esters  of  the  aliphatic  mono carboxylic 
acids  of  even  carbon  content,  lmown  as  the  fatty  acids.  Fats  are 
esters  of  the  triatamic  alcohol  glyceral  while  waxes  are  esters  of 
monatomic  alcohols.  As  a rule  the  alcohols  of  the  waxes  are  of  the 
same  number  of  carbon  atoms  as  the  acids  with  which  they  have  been 
associated,  and  probably  have  their  source  in  the  same  aldehjzde. 

In  order  to  determine  the  various  properties  and  nature  of  fats 
and  waxes,  the  saponification  and  iodine  numbers  are  used  as  con- 
stants. 

The  saponification  or  (XoStsoTffer ) number  is  the  number  of 
milligrams  potassium  hydroxide  used  in  saponifying  one  gram  of  the 
sample.  From  1 to  3 grams  of  the  sample  are  saponified  by  reflux- 
ing on  the  water  bath,  with  alcoholic  KOH  until  the  oil  is  complete- 
ly saponified.  The  excess  alkali  is  titrated  with  standard  hydro- 
chloric acid  and  the  number  of  milligrams  of  potassium  hydroxide  is 
calculated  by  taking  the  difference  between  the  amount  of  acid  need- 
ed to  titrate  the  blank  and  the  amount  needed  to  titrate  the  sample. 
The  saponification  number  is  in  a sense  a measure  of  the  mean  mole- 
cular weight  of  the  mixed  fatty  acids.  The  iodine  number  is  the  per- 
centage of  iodine  absorbed  by  the  fat.  The  official  methods  used  is 
that  of  Hanus  where  a solution  of  iodine  monobromide  in  glacial  acet- 
ic acid  is  used.  This  solution  is  used  because  it  is  more  stable 
than  the  others  and  reacts  more  quickly  with  the  fat.  The  theory  of 
this  constant  is  based  on  the  fact  that  where  we  have  an  ethylene 


- 


T 


u > ' 


. 


- 

. 

V 


t 


•* 


-4- 

linkage,  the  earhon  atoms  will  add  between  them  a mole  of  iodine  or 
a halide  of  iodine,  becoming  saturated*  i’his  holds  true  in  the  case 
of  I Br  dr  ICl  also  since  one  atom  of  iodine  and  one  atom  of  bro- 
mine or  chlorine  will  add  in  the  same  manner  as  two  atoms  of  iodine* 
In  the  calculation,  we  assume  that  the  addition  is  all  iodine* 

‘i’he  method  consists  essentially  in  dissolving  the  fat  in  chlor- 
oform and  allowing  the  solution  to  react  with  a measured  volume  of 
the  iodine  solution  in  a glass-stoppered  Erlenmeyer  flash  for  a def- 
inite length  of  time,  adding  potassium  iodide  solution,  and  titrat- 
ing the  excess  iodine  with  standard  sodium  thiosolfate  using  starch 
as  an  indicator*  A blank  is  run  in  the  same  manner*  jjYom  the  dif- 
ference between  the  blank  and  the  sample,  the  percentage  of  iodine 
is  calculated*  ‘i’his  constant  give  an  exact  measure  of  the  unsatura- 
ted acids  present;  or  rather  of  the  degree  of  unsaturation,  the  high 
er  the  iodine  number,  the  higher  the  per  cent,  of  unsaturated  acids* 


5 


Part  I 

Analysis  of  the  Gasoline  Extract  of  Digitalis  Leaves, 

4 . 

Saponification  Dumber 

The  saponification  number  was  determined  in  the  usual  manner 
by  refluxing  from  one  to  three  grams,  accurately  weighed,  with  25cc. 
of  § alcoholic  potassium  hydroxide.  The  excess  of  potassium  hydrox- 
ide was  determined  by  titration  with  D/2  hydrochloric  acid,  using 
phenol  phtholein  as  an  indicator,  A blank  determination  carried  out 
with  another  25co.  portion  of  the  alcoholic  potash  gave  the  acid  e- 
quivalent  of  the  total  alkali  used.  Owing  to  the  presence  of  so 
much  chlorophyl  in  the  extract,  it  was  very  difficult  to  arrive  at  a 
sharp  end  point  in  the  titration.  Only  by  observing  the  color  of 
the  solution  in  very  thin  layers  could  any  decision  be  made  as  to  the 
completeness  of  the  titration. 

Results: 


Wt.  of  sample  no,  1 — 1.8663  gms. 

" " n 2 - 1.8660  gms. 

" " " " 3 1*8608  gms. 


C.C.  HC1  req.  for  Do.  1 — 5.2 

" " " " 2 5.2 

" ” " " 3 5.15 

saponification  value  for  no.  1 90.8 

" " " " 2 90.7 

n " ” " 3 90.2 

Av.=  §0.5 

25e.c.  alcoholic  EOH  s 28.5c. c.  HC1  D.F  .5106 
This  is  an  exceedingly  low  saponification  value  and  shows  that  the 
extract  consists  chiefly  of  the  organic  solvent  and  chlorophyl  with 


comparatively  little  fat 


Unsaponifiable  Matter.4 

In  this  determination,  the  extract  was  saponified  with  alcohol- 
ic potash,  dealcoholized,  and  the  soap  dissolved  in  water*  The  soap 
solution  was  extracted  three  times  with  ether  to  remove  the  unsapon- 
ifiable  matter,  but  since  chlorophyl  may  be  extracted  from  a soap 
solution  by  means  of  ether,  the  unsaponifiable  matter  had  a green 
color*  The  residue  was  dried  very  quickly  and  weighed*  The  odor  of 
hydrocarbon  oils  was  easily  detected. 

Ke  suits : 

wt.  of  sample  no.  1 3.5304  gms. 

" " " no.  2 3.5824  gms. 

" " residue  no.  1 0.1490  gms. 

" " " no.  2 0.1488  gms. 

per  cent,  unsaponifiable  matter  in  no.  1 4.22 

" " " " "no.  2 — 4.15 

Av.  4.18$ 

The  values  thus  obtained  do  not  represent  the  total  unsaponifi- 
able matter  actually  present,  but  only  that  which  survived  the  heat 
treatments  during  saponification,  extraction  and  drying,  naturally 
a large  part  of  the  unsaponifiable  matter  of  the  original  extract 
consisted  of  gasoline  residues,  much  of  which  would  be  lost  during 
these  operations. 


7 


Iodine  Number 


This  was  determined  by  the  method  of  Hangs  usuing  a solution  of 
iodine  monobromide  in  glacial  acetic  acid.  The  determination  was 
carried  out  in  the  usual  manner,  care  being  taken  not  to  allow  the 
samples  oir  blanks  to  stand  any  longer  than  necessary  because  it  was 
found  that  the  iodine  number  was  lowered  appreciably  upon  standing. 
This  is  due  to  the  absorption  of  oxygen  by  the  unsaturated  fatty 
acids. 


sample 

.Blank 

Na2Sg03 

c * c . 

- used 

Excess 

Iodine  no 

.2590 

87.5 

74.6 

12.9 

79.01 

.2590 

87.5 

74.6 

12.9 

79.01 

.2590 

87.5 

74.6 

12.9 

79.01 

.1250  s N.F.  of  HagSgOg 


Soluble  Acids,^ 


Prom  1 to  5 grams  of  the  sample  were  saponfied,  the  soap  solu- 
tion dealcoholized,  and  made  slightly  acid  with  a measured  excess  of 
standard  hydrochloric  acid.  The  fatty  acids  were  liberated  by  boil- 
ing gently  to  form  a layer  of  oil  on  top.  The  flask  was  cooled,  the 
acid  solution  poured  off,  the  soluble  acids  dissolved  by  washing  the 
oily  layer  with  hot  water  and  the  the  solution  titrated  with  N/10 
alkali  using  phenothalein  as  an  indicator. 


Sample 

c.c.Na  OH 

wt.  of 

per  cent. 

used 

Butyric  acid 

soluble  acids 

1. 

4.5191 

4.12 

.0362 

.802 

2. 

4.5191 

4.12 

.0362 

.802 

3. 

4.5191 

4.12 

.0362 

.802 

.1314  = H.  P. 

Na  OH 

8 


4 

Insoluble  Acids  {Hehner  Number). 

The  flask  containing  the  cake  of  insoluble  acids  was  allowed  to 
drain  and  dry  for  18  hours,  and  the  acids  then  dissolved  in  hot  ab- 
solute alcohol  into  a tarred  dish  after  which  the  alcohol  was  evap- 
orated and  the  dish  and  contents  dried  to  constant  weight.  The  per 
cent,  of  insoluble  acids  was  calculated  from  the  weight  of  the  sam- 
ple used  in  determining  the  soluble  acids. 


Sample  no.  1 s 4.5191  g. 

" no.  2 = 4.5191  g. 

" no.  3 = 4.5191  g. 


per  cent. 

1W1U&?8tCi<iS 

(2)  35.86 

(3)  35.86 


wt.  of  residue  from  no.  1 
" " n no.  8 

" " " " no.  3 


1.6205 

1.6206 
1.6205 


Solid  and  Liquid  IPatty  Acids. 


4 


About  10  grams  of  the  sample  were  saponified  in  the  usual  man- 
ner and  after  neutralizing  the  excess  alkali,  the  lead  soaps  were 
precipitated  with  lead  acetate  solution,  and  treated  with  ether.  The 
soluble  lead  soaps  supposed  to  represent  the  unsaturated  acids  were 
filtered  off  and  decomposed  with  -ether  hydrochloric  acid,  forming 
Lead  chloride  which  was  drawn  off  and  the  ether  solution  evaporated 
Ln  an  inert  atmosphere  to  determine  the  per  cent,  of  liquid  acids. 

The  insoluble  lead  soap  left  on  the  filter  and  in  the  flask 
vas  washed  into  the  flask,  decomposed  with  hot  hydrochloric  acid, 
cashed  with  hot  water,  cooled,  dissolved  in  hot  95$  alcohol,  evap- 
orated, dried  and  weighed  as  solid  fatty  acids.  Only  ten  grams  were 
used  owing  to  the  small  amount  of  fat  in  the  extract. 


1 

/ 


/ 


c 


9 


wt.  of  solid  per  cent 
acids  solid  acids 
.0839  1.85 

.0839  1.85 


wt.  of  liquid 


per  eent 
liquid  acid 


1.  9.0382 

2.  9.0382 


Sample 


acids 

.3575 

.3577 


7.91 

7.91 


Iodine  number  of  Liquid  ratty  Acids 


1.  .3575 

2.  .3577 


Sample 


c.c.  used 


25.1 

25.1 


Iodine  no 
106.09 
106.09 


B.  I5,  of  Ba2S203  -.11905 


Part  II 


Analysis  of  gasoline-free  and  chlorophyl-free  Pat 


In  order  to  attack  this  part  of  the  work,  50  grams  of  the  ex- 
tract were  saponified  with  alcoholic  potassium  hydroxide,  and  the 
alcohol  boiled  off  completely  while  frequently  adding  small  amounts 
of  water  to  replace  the  alcohol.  The  soap  was  diluted  with  water, 
acidified  with  sulfuric  acid,  and  boiled  gently  to  set  free  the  fat- 
ty acids  from  their  potassium  salts.  A thick  black  layer  formed  on 
top.  This  layer  consisted  of  the  fatty  acids  and  chlorophyl.  Since 
it  was  a hard  cake,  a hole  was  punched  thru  it  and  the  acid  solution 
poured  off.  The  cake  of  acids  and  chlorophyl  was  then  dissolved  in 
an  aqueous  solution  of  sodium  hydroxide  to  form  the  sodium  salts  of 
the  fatty  acids.  Since  these  salts  are  insoluble  in  ether,  or  only 
slightly  soluble,  and  since  chlorophyl  is  soluble  in  ether,  the  al- 
kaline solution  was  poured  into  a separatory  funnel  and  repeatedly 
extracted  with  ether.  The  soap  solution,  free  from  chlorophyl  had 
a light  brown  color.  This  solution  was  boiled  gently  with  dilute 
sulfuric  acid  until  a clear  brown  layer  of  fatty  acids  formed  on  top. 
The  remainder  of  this  work  was  done  on  the  fats  obtained  in  this  man- 
ner. Very  small  amounts  were  used  and  the  work  done  very  carefully 


O 

1 

i 

r * 

- 


10 

because  only  three  grams  of  fat  were  obtained  from  50  grams  extract. 
The  fat  was  not  absolutely  free  from  gasoline. 

Iodine  Number  of  Purified  Patty  Acids. 

Carried  out  in  the  usual  manner  as  already  described. 

Sample  Blank  Excess  c.c.  used  Iodine  no. 

Na^SpOa 

1.  .8713  94.95  31.70  63„25  114.2 

1.  .8713  94.95  31.70  63.25  114. E 

N.F.  Na2S203  « .1239 

Saponification  Equivalent  of  Purified  Patty  Acids. 

Carried  out  in  the  usual  manner  as  already  described. 

c.c.HCl  c.c.HCl  c.c.HCl  Saponification 

for  blank  for  excess  used  by  sample  Equivalent 
70.3  66.5  3.8  146.9 

70.3  66.5  3.8  146.9 

N.F.  of  HC1  I .5106 

Unsaponifiable  Matter. 

The  solution  remaining  from  the  determination  of  the  saponifi- 
cation equivalent  was  again  made  alkaline  and  extracted  repeatedly 
with  ether.  The  ether  was  evaporated  and  the  residue  resaponified 
with  alkali.  This  soap  solution  was  then  extracted  with  ether  to 
determine  the  true  unsaponifiable  matter. 

Sample  wt.  of  residue  per  cent 

unsaponifiable  Matter. 

1.  1.0398  .1786  17.18 

2.  1.0397  .1785  17.18 

These  results  express  the  per  cent,  of  unsaponifiable  matter 
including  hydrocarbon  residues  from  the  gasoline.  To  remove  the 
hydrocarbon  oils  from  the  total  unsaponifiable  matter,  the  residue 
was  boiled  with  95$  alcohol,  cooled,  filtered,  and  the  filtrate  e- 
vaporated,  dried  and  weighed. 


Sample 
1.  1.0398 
2 1.0397 


11 


Sample  wt.  of  residue  per  cent  of 

unsap.  matter  in  pure 
fatty  acids. 

1.  1.0389  .0159  1.53 

2.  1.0397  .0156  1.53 

These  results  express  the  per  cent,  of  unsaponif iable  matter  of 
the  phytostdrol  type  in  the  pure  fatty  acids  containing  no  hydrocar- 
bon oils  or  chlorophyl. 

Calculation  of  Mean  Molecular  Weight  of  Purified 
Mixed  Patty  Acids 

The  neutralization  value  of  the  purified  mixed  fatty  acids  is 
not  expressed  by  the  saponification  equivalent  of  146.9  because  the 
fatty  acids  used  in  determining  the  saponification  equivalent  con- 
tained 17.18$  unsaponif iable  matter.  The  actual  weight  of  fatty  acid 
;itrated  is  0.8610  gmt  and  the  weight  of  potassium  hydroxide  consumed 
per  gram  of  acid  is  0.1264  gm. 

Formula : 

M-  mol.  wt.  expressed  in  grams,  (theory  requires  that  M 
grams  be  neutralized  by  56.1  grams  potassium  hydroxide) 

Ifs  no.  grams  of  potassium  hydroxide  required  to  neutralize 
1 gram  of  pure  fatty  acids.  Then  we  have  the  proportion 
M:56.1::l:n;  hence  Ms  56.1  1 

0.1264  Ms  444.2 


IE 


Melting  Point  of  Pure  Patty  Acids 

Ho  melting  point  was  taken  because  the  free  fatty  acids  were 
liquid  after  standing  48  hours  at  room  temperature. 

Conclusions. 

Since  only  3 grams  of  fatty  acids  were  obtained  from  50  grams  of 
the  gasoline  extract,  it  is  evident  that  the  extract  contains  a very 
small  amount  of  fatty  acids.  The  bulk  is  made  up  of  gasoline  and 
chlorophyl.  The  solution  may  be  freed  from  the  organic  solvent  by 
evaporation  on  the  water -bath  under  diminished  pressure.  To  obtain 
the  free  fatty  acids,  it  is  necessary  to  saponify  the  extract  with 
alcoholic  potassium  hydroxide,  and  boil  with  dilute  sulfuric  acid  un- 
til the  oily  layer  floats  on  top.  This  oily  layer  consisting  of  fat- 
ty acids  and  chlorophyl  is  then  treated  with  an  aqueous  solution  of 
sodium  hydroxide  and  repeatedly  extracted  with  ether  to  remove  the 
chlorophyl.  After  all  the  chlorophyl  has  been  removed,  the  free  fat- 
ty acids  may  be  liberated  by  again  adding  dilute  sulfuric  acid  and 
boiling  until  the  oily  layer  appears.  The  free  fatty  acids  may  then 
De  extracted  with  ether,  the  ether  evaporated,  and  the  fatty  acids 
iried. 

The  small  amount  of  free  fatty  acids  in  the  extract  is  accounted 
for  by  the  fact  that  most  vegetable  fats  and  oils  are  found  in  the 
seeds  and  kernels,  and  not  in  the  leaves. 

The  iodine  value  of  the  mixed  fatty  acids  is  114.2  and  that  of 
the  liquid  fatty  acids  is  106.09.  The  liquid  fatty  acids  are  supposed 
to  represent  the  unsaturated  acids.  Therefore,  most  of  the  mixed  fat- 
ty acids  are  unsaturated.  An  iodine  number  of  114. E is  too  low  to  en- 
able the  oil  to  be  classed  as  a drying  oil.  This  value  classes  the 
nixed  fatty  acids  as  a semi-drying  oil.  The  mixed  fatty  acids  when 


13 


left  exposed  to  the  atmosphere  for  48  hours  formed  a very  thifl  scum 
or  membrane.  This  is  characteristic  of  a semi -drying  oil. 

After  removing  the  unsaponifiable  matter  from  the  mixed  fatty 
acids  and  calculating  the  true  neutralization  value  the  mean  molecu- 
lar weight  was  found  to  be  444. E.  These  values  correspond  very  close- 
ly to  a mixture  of  erucic  acid  with  a mean  molecular  weight  of  338 
and  a neutralization  value  of  166  with  some  polymerized  products 
formed  during  the  extractions.  This  classes  the  fatty  acids  with  the 
solid  waxes  which  have  acidswith  molecular  weights  of  over  300.  The 
presence  of  hydrocarbon  residues  from  gasoline  perhaps  prevented  the 
fatty  acids  from  solidifying.  Although,  these  hydrocarbon  residues 
were  present,  the  mixed  fatty  acids  in  their  free  state  became  viscid, 
thus  showing  a tendency  at  least  to  become  solid. 


* 


“ ' 


. . 


- 


. 


17 


BIBLIOGRAPHY 


1*  United  States  Pharmacopoeia. 

(9th  decennial  Revision) 

2.  Lewkowitsch,  Technology  of  Oils, 

Pats,  and  Waxes. 

3.  Sherman,  Organic  Analysis. 

4.  Methods  of  Analysis,  Association 

of  Official  Agricultural  Chemists. 


